Frictional pressure drop Darcy equation

Another definition of friction factor is that used in the Darcy equation for pressure drop. The Darcy friction factor, f, is defined as... 

The single-phase friction loss (pressure drop) for these situations in chemical and petrochemical plants is still represented by the Darcy equation with specific limitations [3] ... 

The frictional resistance or pressure drop due to the flow of Lhe fluid, hf. is expressed by the Darcy equation ... 

Chemical engineers are familiar with the Fanning (or Darcy) friction factor,/, the Moody chart of/vs. Reynolds number, Rg, and how all of this fits together to calculate pressure drop for a given fluid flow in a given sized pipe. The friction factor is calculated from the Colebrook equation ... 

The friction factor is used in the Darcy-Weisbach equation for calculation of pressure drop for turbulent flow in an empty pipe. The mixer pressure drop is given by... 

In the above equation, L is the length over which the pressure drop p — p2 is to be calculated pi is the absolute pressure of the flow at an upstream point 1, and p2 is the absolute pressure of the flow at a downstream point 2 / is the Darcy-Weisbach friction factor that can be determined from the Moody Diagram y is the adiabatic exponent (equal to 1.4 for air) and Mi is the Mach number of the flow at the upstream point 1. In addition to the pressure equations, the following equation of state of ideal gas is also needed ... 

The approach to obtain the magnitude of is basically to conduct a test and measure pressure drop per unit length of pipe. V3 is considered to occur at the minima, or the point of minimum pressure drop. W. E. Wilson (1942) expressed the pressure gradient of non-colloidal solids by referring to clean water and by proposing a correction to the Darcy-Weisbach equation (discussed in Chapter 2). He expressed the consumed power due to friction by the following equation ... 

Many equations are available to show the relationship between fluid flow and pressure drop in a given pipeline. The equations typically involve a friction factor that is dependent on the pipe materials. Darcy-Weisbach and Hazen-Williams are commonly used equations. 

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